Performance evaluation of rate-aware multiuser two-way fixed gain relay networks

In this paper, we study the performance of multiuser two-way relaying (TWR) system in cellular environment, wherein an N
_a
-antenna base station (BS) wants to exchange information bidirectionally with one of the several single-antenna users (USs) with the aid of a fixed gain single-antenna relay terminal under different target rate requirements. In particular, we employ maximal ratio transmission (MRT)/maximal ratio combining (MRC) beamforming (BF) at the BS with user scheduling that maximizes the end-to-end signal-to-noise ratio (SNR). We deduce a new expression for the exact overall outage probability (OOP) of the considered system under independent and identically distributed (i.i.d.) Rayleigh fading channels. Moreover, we also derive a closed-form expression for the sum symbol error rate (SSER) to analyze the system error performance under various modulation schemes. Finally, the analytical findings are validated by the numerical and simulation results, and reveals that the diversity order of the considered system is independent of traffic asymmetry and decided by the minimum of the number of BS antennas and the number of USs.